diff --git a/check.sh b/check.sh
index e114b0d..f1f49d5 100755
--- a/check.sh
+++ b/check.sh
@@ -108,7 +108,22 @@ if [ "amd64" != "$(dpkg --print-architecture)" ]; then
 fi
 
 if [ $# -ne 8 ]; then
-	echo "usage: $0 pkgtype provides pkgaarch pkgbarch pkgama pkgbma debrel debvpkg" >&2
+	echo "usage: $0 [pkgatype pkgbprovides pkgaarch pkgbarch pkgama pkgbma debrel debvpkg]" >&2
+	echo "" >&2
+	echo " * pkgatype     is the type of pkga and can be one of binary or source" >&2
+	echo " * pkgbprovides is the provides field of pkgb and can be anything like none (no provides), pkgc, pkgc:amd64 or pkgc:i386" >&2
+	echo " * pkgaarch     is the architecture of pkga and can be any valid architecture or none in case pkga is a source package" >&2
+	echo " * pkgbarch     is the architecture of pkgb and can be any valid architecture" >&2
+	echo " * pkgama       is the multi-arch value of pkga and can be any valid multi-arch value or none in case pkga is a source package" >&2
+	echo " * pkgbma       is the multi-arch value of pkgb and can be any valid multi-arch value" >&2
+	echo " * debrel       is the relationship of pkga to pkgb and can be one of depends or conflicts" >&2
+	echo " * debvpkg      is the dependency relationship value and can be any anything like pkgb, pkgb:amd64, pkgb:i386, pkgb:any, pkgc, pkgc:amd64, pkgc:i386, pkgc:any, pkgb:native or pkgc:native" >&2
+	echo "" >&2
+	echo "If no arguments are given, then all legal permutations are printed to standard output, each on one line." >&2
+	echo "" >&2
+	echo "This allows one to test all situations like this:" >&2
+	echo "" >&2
+	echo "$ ./check.sh | xargs --max-procs=8 --max-lines=1 ./check.sh 2>/dev/null" >&2
 	exit 1
 fi